FIG. 1 shows a known device 100 for aiding flight management installed on board an aircraft. This device conventionally comprises a flight management system FMS 2 capable of constructing a flight plan. Conventionally, a flight plan defines the route that the crew of an aircraft plans to follow in order to go from a starting position to a destination point of its mission and the conditions for travelling this route. The flight plan is defined by geographic elements of the flight plan, namely a succession of waypoints WP connected by straight or curved segments called “legs” and elements associated with various flight requirements of heading, of altitude, of speed, of passage time, etc. that must be adhered to by the aircraft when it passes over or in their vicinity. The flight plan also comprises a lateral trajectory and a vertical trajectory in the horizontal plane and respectively in the vertical plane. In the rest of the text, elements of the flight plan will refer to the geographic elements of the flight plan, the elements associated with flight requirements and the lateral trajectory and the vertical trajectory of the flight plan.
The flight management system FMS, 2, conventionally comprises:                location means LOCNAV, 170, for locating the aircraft based on information transmitted by geolocation means GEO, 220, of the aircraft which comprise for example satellite positioning receivers, radiofrequency beacons, inertial navigation units;        means 110, 130, 150 for storing flight parameters comprising:                    means FPLN, 110, for storing the geographic elements of the flight plan, constituting the skeleton of the route to be followed, input by the crew by means of the on-board console MCDU, 3, which will be described hereinafter,            a navigation database NavDB, 130, updated every 28 days, capable of storing standard data essential to the construction of the flight plan, based on standard data supplied by the aviation authorities (the method for feeding the base is as follows: supply of the aviation data by the States or delegated bodies, conversion to the A424 format for the suppliers of data of the EAG, Jeppesen or LSY type, then conversion to a binary format that is optimized and the property of each FMS manufacturer),            a performance database, PerfDB 150, containing the aerodynamic and engine parameters of the aircraft,                        computing means 120, 140 for constructing the flight plan based on the data stored in the storage means 110, 130, 150, the said computing means 120, 140 comprising:                    a module for constructing a lateral trajectory TRAJ, 120, for constructing a continuous lateral trajectory based on the geographic elements of the flight plan, complying with the aeroplane performance and the requirements stored in the navigation database NavDB 130,            a module for constructing a vertical trajectory PRED, 140, for constructing a vertical profile optimized on the lateral trajectory complying with the performance of the aeroplane and the requirements stored in the navigation database NavDB, 130,                        a guidance module GUID 200, for generating guidance commands making it possible to guide the aircraft in the lateral and vertical planes along the flight plan, while optimizing its speed, the guidance commands then being transmitted to the pilot or to an automatic pilot not shown,        a ground/aircraft communication system called CMU (the acronym for “Communication Management Unit”), 180, allowing the flight management system to communicate with stations based on the ground, in particular air traffic control ATC stations, 370, or airlines or else to communicate with other aircraft.        
The elements of the FMS are conventionally connected together but the links between these elements are not shown for greater clarity.
The standard data stored in the navigation database comprise published navigation procedures NavDB (for example, take-off or landing procedures, air routes) that the aircraft may be required to comply with in the space in which it operates. The standard data also include information concerning airports, runways and radionavigation beacons.
Conventionally, the aircraft is connected to a man-machine interface 3 called the MCDU (“Multipurpose Control Display Unit”), 3, which is a data input and display console comprising manual inputting means 4, comprising keys, allowing the crew to enter data into the said console, to select zones displayed on a display called the navigation display ND, 5, and to activate the selected zone in order to initiate operations that relate to what is displayed. The navigation display ND, 5, is capable of displaying a window (optionally occupying the whole display) dedicated to navigation, comprising (graphic and optionally textual) representations of elements of the flight plan in a geographic space called the display zone ZA such as, for example, the lateral trajectory and/or of the lateral trajectory and the various waypoints WP of the position of the aircraft. Representations (which may be graphic and optionally textual) of data stored in the navigation database may also be displayed. The window dedicated to navigation helps the crew to follow the flight plan. It is displayed automatically or on command of the crew using the manual inputting means.
Navigation-aid data that are distinct from the standard data of the navigation database NavDB are also useful to the pilot for completing his mission. They involve, for example, textual information relating to the route, to the airport of departure or arrival, air traffic management (ATM) data (sector limits, safety altitudes at given positions, airspace divisions), data relating to towns, rivers, forests, borders between countries, high-voltage lines, motorways.
The navigation-aid data are currently available in documents available in paper form on the flight deck or in an electronic flight bag (EFB), replacing the paper documentation and being disconnected from the flight management system FMS and from the flight console MCDU. However, consulting the aforementioned information in these media is time-consuming for the pilot. Moreover, it is difficult to find and take account of the information that is of use to the pilot during his mission. For example, it is necessary to carry out calculations, based on the current position of the aircraft and on information showing a border with a country over which flying is banned, in order to ensure that the aircraft does not penetrate the banned airspace. This calculation represents a risk factor because, on the one hand, it requires the attention of the crew and, on the other hand, it is approximate. Certain corporate aeroplanes superpose a map over their navigation display ND corresponding to a cartographic background representing the ground situated beneath the flight plan. However, this information is fixed; it is not necessarily useful to the crew. Moreover, it is difficult to create a background which on the one hand does not overload the navigation display and, on the other hand, presents all the information useful to the pilot during his mission.